1. Field of the Invention
The invention pertains to an inverter-based power supply device designed to supply power to a load with variable impedance. The invention can be used especially in the field of induction heating in domestic cooking. Indeed, the shape and the material of the kitchen utensils that can be heated by induction are giving rise to major changes in the load that is powered by the power generator.
2. Description of the Prior Art
Many devices, such as for example the one described in the patent application EP 0 405 611, set up an automatic control over the power delivered by a generator, so that it may be a function solely of an instructed value given by the user, independently of the material and shape of the utensil. To achieve this goal, the electronic components of such structures must be oversized, and this increases the cost of making such devices. Furthermore, certain kitchen utensils may have particular impedance values that can endanger the generator, for example by destroying certain electronic components. To overcome this danger, certain generators, such as for example the one described in the patent application EP 0 561 207, use a safety system that stops the generator if the current, in certain electronic components, exceeds an acceptable maximum value. This type of safety system totally rules out the use of certain utensils which nevertheless could be used by limiting the current delivered by the generator.
The invention seeks to control the power delivered by the generator. At the same times it seeks to enable the generator to deliver the maximum power without endangering it and approach, as far as possible, the instructed value of power given by a user.